[].keys() and [].items() (Was: Why I think range is a wart)

[Clark C . Evans]

On Thu, Mar 14, 2002 at 12:18:13AM +0000, Huaiyu Zhu wrote:
| On Wed, 13 Mar 2002 22:39:02 GMT, Terry Reedy <tejarex at yahoo.com> wrote:
| >> I would like to see:
| >>     .keys()
| >>     .items()
| 
| Question:  Which is better:  items(x) or x.items()?

Does it have to be mutually exclusive?  Python has
a tradition of enabling both mechanisms.

| I think items(x) can just piggy-back on the current iterator protocol, and
| can be made to work on any iteratable objects.

Would "keys()/items()" be compatible with the iterator proposal? 
It would be extending the iterator to return pairs... this might
be a bit divergent...

| On the other hand, x.items() has to be implemented by each and every
| list-like classes.  Their subclasses need to override them whenever
| necessary. 

I like x.keys() and x.items() since it is _currently_ how
maps work already... extending the behavior to lists makes
sense to me and I don't have to "think about it".
As for the implementation difficulty, a generic "mix-in"
implementation can be provided; or even more simply one
could just assign self.items = items; self.keys = keys.

| So else being equal, I'd prefer items(x) to x.items().

I don't see why we can't have our cake and eat it too. ;)

| Question:  Which is better name: keys or indices?  items or indexed?  

I have a strong opinion here... use the same function 
names as used by a map!  A list is really just a map
such that the domain is limited to positive integers.
Having a different set of names isn't a good idea.

| I think the latter two (indices, indexed) are more descriptive of sequence
| types.  This is especially true if one ever want to use a seqdict type.

Ick.

| Question: Which name is better: iterkeys or xkeys?

Which ever works for maps; the decision should be shared
as a list is a special map with a limited domain.

Best,

Clark